Explosive flashlight



p 1953 5. H. MESSERLY ET AL 2,653,073

EXPLOSIVE FLASHLIGHT Filed Nov. 7, 1946 awe/ms, Ben E HLMEE 1g and firch W Eam h 1 my MMZMM ms Patented Sept. 22, 1953 EXPLOSIVE FLASHLIGHT George H. Messcrly, Staten Island, N. Y., and, Arthur W. Campbell, Santa Fe, N. Mex., assignors to the United States of America as represented by the Secretary of the Army Application November 7, 1946, Serial No. 708,390

11 Claims. 1

This invention relates to a new and useful improvement in methods of photographing detonation phenomena.

The essential feature of our improved method of photographing detonation phenomena is the production of a light of determined luminosity and period of duration by the detonation of a charge of explosive, which detonation is produced in determined time relation to the detonation of the charge of explosive the phenomenon of which is to be photographed. The essential features of our improved method of producing the flash bulb, for use in practicing our improved photographing method, are the production of the explosive charge and a translucent envelope therefor, so relating them as to provide an area between the charge and envelope, and charging this area with a gas having positive luminous shock Wave properties, the luminosity and period of duration of the light produced by the explosive charge being precisely determined by the character of the charge, envelope and gas and their mutual relationship. The essential feature of our improved flash bulb, produced by our improved method, is the combination of the charge, envelope and gas comprising the bulb.

It has been known that the degree of luminosity of light produced by detonation of a charge of explosive is markedly influenced by the atmosphere surrounding the charge. The light is produced in the shock wave ahead of the expanding products of detonation. The gas in this shock wave front undergoes an adiabatic compression and the temperature attained depends 'on the value of the heat capacity ratio for the atmosphere in which the shock wave travels. For a given temperature, the light-emitting power of the gas is, in general, greater for the gases of higher density. Thus, for maximum light intensity, the higher density rnonatomic gases are most effective.

As far as we know, the high intensity flash, produced by detonating a charge of explosive, had not been used as the light source for flashlight photography of detonation phenomena, prior to our invention of our improved method using such flash. The successful practice of our improved method of photographing detonation phenomena, by the use of the light produced by detonating an explosive charge, has demonstrated the superiority of our method over those in which spark lighting is used, since in our method the degree of luminosity and the period of duration of the flash, and the timing of the detonation producing the flash are all subject to 2 easy, precise and effective control to a degree not possible in prior known methods. We have successfully produced photographs of detonation phenomena, by our improved method, using our improved flash bulb produced by our improved method of production, which produced a light having a photographic intensity of 10 candlepower and a period of duration of 10- seconds. In producing the said photographs use was made of the method and apparatus for covering a camera lens disclosed and claimed in co-pending application Serial Number 646,454, filed February 8, 1946, now Patent 2,470,139, dated May 17, 1949.

We have illustrated in the drawing filed herewith and have hereinafter fully described one specific embodiment of our invention as to our improved flash bulb produced by our improved process, and also certain instrumentalities for use with our improved bulb for practicing our improved photographing method. It is to be distinctly understood that we do not consider our invention to be limited by the disclosure of said specific embodiment but refer for its scope to the claims appended hereto.

In the drawings:

Figure 1 is a section of a mold suitable for producing the complementary halves of a spherical charge of explosive for the flash bulb.

Figure 2 is a section showing the charge halves and a foil-wrapped detonator fuze prior to assembly.

Figure 3 is a perspective of a transparent flaslc. in two sections, to serve as the envelope for the.-

'cylindrical groove A-3 radiating from the periphery of concavity A-2, and a cope A- l having a semi-cylindrical core A-5 corresponding to groove A-3 and extending radially into concavity A-Z. The mold A produces a spherical charge I comprising the hemispherical halves 2 and 3, each having the semi-cylindrical groove 4 which, when the halves 2 and 3 are united, form the cylindrical borei. As shown in Figs. 2 and 4, a

which is disposed concentrically in the envelope- 8 by means of spacers H of any suitable material, such as cork. The fuze 6 with--its=end= wrapped in foil 1 is held in place in: neck l-2 ofenvelope 8 by suitable split plugs-213,2,

After the charge I with its-fuze fi has; been-.dis.-- posed in proper relation to portiom'xili and neck." l2, the portions 9 and i areconnected by any. suitable translucent bonding medium I 5, such" as collodion or Scotch tape, to completely'jas semble the flash bulb It? It will be noted that the spacers l I provide .a-space 8-A the-envelope Bbetween. theaouter surface l-Aof the charge I and the-innersurfaceB-b-ofthe envelope '8, and by reason of the-fact that the spherical-chargel and the spherical envelope 8 are concentricallyrelatively disposed, the spacers ll being of uniform: thickness, this space- B-A has uniform dimension radially of the spherical charge.- This-space-.8+a, isfilled, through opening ll in theenvelope-B; with a gas having positive luminous shock wave properties, such as argon which proved very satisfactory in the actual practicea of-- our/improved method; The method:for:chargingtheenvelope 8 Withthe argon was as-follows. The bulb IG-was placed-in a desiccator; (not-shown) from which air was evacuated and:v replaced-.by argon; which passed through opening :I 1 .to fill space-ll-A, the opening i! then. being-closed; The bulbl 6-was :placed in desiccator until immediatelygbefore use, thereby minimizingloss-of argon fromv envelope 8.

Since the blast from detonation of, charge 18 of the explosivethesphenomenonof which is..-to be photographed is intenselyself-luminous in air, it is necessary that charge l8-be detonated in. an atmosphere: having. negative luminous shock wave properties. Charge :l8'.is:housed in a suitable translucent sealedienvelope-cl8-a such as a bag of cellulose acetate which proved very: satisfactory '.inthe practice of-our 'improvedfmethod, and suitable gas, such as ether vapor or propane;- butane gas, issupplied to v.envelope I8+a'through hose l9introducedinto envelope lea.- to produce an atmosphere havingthe desired negative-luminous shock'wave-properties.

The bulb I6 containing charge I, and the envelope [8-0. containing charge [8 aresuitably disposed in a light-proof and bomb-proof chamber 20. A photographing means H, such' as'a camera, issuitably. positioned inxchamberlll-a in the wall of chamber 20; relative to bulb I6 and envelope I8-a. Means is operative through and protected byatransparent bullet -proof window 22. The bulb. I6. is provided with. a, suitably disposed reflector; 23..

The timingof the-firingof chargesl and. I8 is determined by varying the relative-lengths. of the. prima. cord; fuzesifi 3and24 connected to the chargesl and 18 respectively.

Having describedourinvention,-what we claim 1.. That methodof; determining detonation phenomena of an explosive comprising idetonating atest specimen; of. saiduexplosive,substantially simultaneously. detonatingaa second charge -of 4 explosive while enveloped in a gas having positive luminous shock wave properties, and photographing the detonation of said test specimen by the light aliorded by the detonation of said second charge of explosive.

2. That method of photographically determining thedetonation characteristics of a first explosive,. comprising, simultaneously detonating a second explosive in an atmosphere having positive luminous shock wave properties, and photographing the detonation of said first explosive b'y-the-illumination afforded by the detonation of: said-second explosive.

3.: That method of photographing detonation phenomenaof favfirst explosive charge, comprising, "detonating in: predetermined timed relation with detonation of said first explosive charge a second explosive charge surrounded by a gaseous..=monatomic element having positive luminous shock wave properties and positioned adjacent said firstcharge, andsphotographingj'the detonation of said first charge-by the illumination afforded by said second charge.

4." That method of determining detonationphenomenaof a first explosive charge, comprising, detonating substantially simultaneously with detonation of said first explosive charge, a second explosive'chargesurrounded by a gaseous medium having positive luminous shock Wave properties and positioned adjacent said first explosive charge, and photographing the detonation of said first explosive charge by the=illumination provided by said second explosive charge.

5. The method. of-photographing the detonation of a first'charge ofexplosive to be tested, comprising, detonating said first-charge while enveloped in an atmosphere having negative luminous shock wave properties, substantiallysimultaneously detonating. a second charge ofrexplosive surrounded by an atmosphere having positive luminous shock Wave properties, and photographing the detonation of said first charge by the illumination afforded by the detonation of said second charge,

6. That method of testing the detonation characteristics of an explosive, comprising, detonating a charge of said explosive in an atmosphere havingnegative luminous shock wave properties, and photographing said. detonation: by the illumination afforded by the substantially simultaneous detonation of a second charge of explosive in an atmosphere having positive luminous shock wave properties.

'7; In. an apparatus for testingdetonationcharacteristics of an explosive, means for supporting a' charge :of said explosive Within an atmosphere of' gas having negative luminous shock wave properties,;a second charge of illuminating explosive, meanssupportingsa'id second charge adjacent saidifirst chargewithin an atmosphere of--'gas having positive luminous shock wave properties, and means to detonate said charges in predetermined timed relation.

8. in an. apparatus for photographing the deton'ation: characteristics of anaexplosive, camera means, means supporting a charge of said explosive in-position to be photographed by=said camera means, illuminatingv means comprising a secondicharge of explosive, a flask of light-transmitting material, means mounting said: second charge within said flask in spacedrelation: with the inner walls. thereof 'toprovide a space-en.- velope thereabout. adapted .to be filled with a gas having positive aluminous shock wave properties,

meanszmounting said. flask adjacent saidzexplw sive charge to be tested, and means operable to detonate said charges substantially simultaneously.

9. In an apparatus for photographing the detonation characteristics of explosives, a camera, a first translucent container, a, specimen charge to be detonated, means suspending said charge Within said container in position so that the detonation thereof may be photographed by said camera, an illuminating charge of explosive, a second translucent container, means supporting said illuminating charge within said second container in spaced relation with the walls thereof, means supporting said flask in position adjacent said container, and means to detonate said two charges substantially simultaneously.

10. An apparatus as recited in claim 9, and a gas having positive luminous shock wave properties confined in said second container.

11. An apparatus as recited in claim 10, and

a gas having negative luminous shock Wave properties confined in said first container.

GEORGE H. MESSERLY. ARTHUR W. CAMPBELL.

References Cited in the file of this patent UNITED STATES PATENTS 10 Number Name Date 1,936,595 Goddard Nov. 28, 1933 2,116,423 Korver Apr. 26, 1938 2,129,001 Goehner Sept. 6, 1938 2,305,609 Eaton Dec. 22, 1942 15 2,323,301 .Anderson July 6, 1943 2,377,292 Donaldson May 29, 1945 OTHER REFERENCES Fast Photos, Scientific American, Septem- 20 her 

